Foil Winding Resistance and Power Loss in Individual Layers of Inductors

Power transformer in the voltage-fed single-stage full-bridge (SSFB) converter is easy to be saturated because of the special operating mode of this topology. First and foremost, detailed analysis about the generation mechanism of the transformer saturation in the voltage-fed SSFB converter is presented for the first time in this paper. Second, the mathematical expression of the maximum value of magnetic flux density bias (MFDB) during every line cycle is deduced. Furthermore, a novel suppressing strategy, consisted of the digital compensating algorithm and design considerations, is proposed based on the theoretical analysis and mathematical expression. The MFDB can be eliminated and additional circuits are not needed with the proposed strategy. Finally, a 1 kW prototype with the voltage-fed SSFB topology is built to verify the effect of the proposed approach. The voltage-second imbalance is reduced to less than 1% using the proposed suppression strategy compared with 14% when the strategy is not used. Consequently, the system reliability and the efficiency are improved. research is seldom studied comprehensively. In [10], the flux density bias problem is mentioned, and a protection circuit is used to limit the maximum magnetizing current. Detailed theoretical analysis is not involved, and the efficiency is still affected.In this paper, the generation principle of the MFDB is analyzed in detail. Then the mathematical expression of the maximum MFDB is deduced. Based on these theoretical analyses, a novel strategy is developed to avoid the transformer saturation in the voltage-fed SSFB converter. The paper is organized as follows. In Section 2, the principle of flux density bias generation is analyzed. Besides, the maximum MFDB is calculated in this section. Section 3 gives several conventional solutions for suppressing the MFDB. The proposed suppressing strategy including design consideration is presented in Section 4. In Section 5, a 1-kW prototype with voltage SSFB topology is built and tested. With the proposed strategy, the system reliability is improved, and the efficiency is increased. The conclusions are given in Section 6. GENERATION MECHANISM OF THE MFDBThe circuit diagram of the voltage-fed SSFB converter is shown in Figure 1. The two bridge legs of the full-bridge converter are composed of four transistors, Q 1 , Q 2 , Q 3 and Q 4 , in which, Q 2 and Q 4 are also used to perform the same current-shaping function as the switch in a boost converter. Components D S1 , D S2 , L 1 and L 2 make up a semi-bridgeless converter. The power transformer T r , resonant inductance L r (including the leakage inductance), output rectifier diodes D R1 and D R2 , output filter inductance L O and capacitance C O make up a standard full-bridge converter [11][12][13]]. An energy store capacitor C F is placed across the primary-side dc bus. MFDB generation mechanismThe MFDB occurs when the voltage-second balance of the magnetizing inductance is not achieved. Actually, this phenomenon may occur in most full-bridge converter b...

“…The losses of the high frequency transformer can be divided into core loss and winding loss [31][32][33][34]. The hysteresis core loss can be expressed as [31] …”

Section: Transformer Loss Analysismentioning

confidence: 99%

Magnetic flux density bias analysis and suppression strategy for voltage‐fed single‐stage full‐bridge converter

Zhang

Qian

et al. 2016

“…In particular, if the series resistance of the inductor ρ L can be related to inductance l, using, for example, a theoretical model accounting for various constructions of inductors [16][17][18], proximity effect [19] or harmonic contents [20], then the derived corrections allow to find the optimal inductance l. Being able to estimate the impact of the internal battery resistance enables determination without simulation or prototyping whether a particular kind of batteries is suitable for an application. In particular, if the series resistance of the inductor ρ L can be related to inductance l, using, for example, a theoretical model accounting for various constructions of inductors [16][17][18], proximity effect [19] or harmonic contents [20], then the derived corrections allow to find the optimal inductance l. Being able to estimate the impact of the internal battery resistance enables determination without simulation or prototyping whether a particular kind of batteries is suitable for an application.…”

Section: First-order Correctionsmentioning

confidence: 99%

Modelling of battery‐powered boost DC–DC power LED driver with parasitics by multivariate power series expansion

Rudziński

2014

This paper presents an analytic model of a battery-powered boost DC-DC converter driving a power light emitting diode. The model is capable of taking into account parasitic components, including series resistances, parasitic capacitances and inductances. Unlike the standard approach to the converter modelling, the discussed model does not require any assumptions concerning current and voltage waveforms. It is based on power series expansion in normalized values of the parasitic components, leading to expressions comprising only physical parameters of the circuit. First-order corrections are derived and illustrated in this paper.

“…The resistance of a multiturn coil depends on the distribution of the current over the conductor crosssection, which is determined by two factors: the skin effect, which causes for high frequencies a concentration of the current near the outer surfaces of the conductor, and the proximity effect, due to currents in adjacent conductors, which forces the current to the outside edges [22][23][24][25][26]. The latter is particularly important for systems with several closely spaced conductors, as the variation in the current distribution can increase the resistance of the conductors with a contribution even larger than that produced by the skin effect.…”

Section: Resistancementioning

confidence: 99%

Equivalent circuit characterization of resonant magnetic coupling for wireless transmission of electrical energy

Sandrolini

Reggiani

Puccetti

et al. 2013

This paper provides the accurate characterization of a wireless power transfer system consisting of two resonant air-core coils mutually coupled in free space. The lumped-circuit parameters of the equivalent circuit are determined with analytical formulas taken from the literature and validated by comparison with numerical simulations with a finite-element computer code and with experiments. The parameters are determined taking as input only the geometry of the system (coil size and mutual distance, conductor radius, and turn distance) and the frequency. Once the lumped-circuit parameters are known with good accuracy, the assessment of the power transfer system can be carried out by evaluating the current and voltage gains and efficiency for different system geometries, operating frequencies and load conditions. The Scilab programming environment was used to perform all the calculations. The characterization presented in this paper can then be considered as an effective tool in designing an efficient wireless power system. identification systems [8], or mobile appliances such as portable computers or mobile phones [9]. In general, the applications can be divided into two main areas: direct wireless powering of stationary or dynamic devices and automatic wireless charging of portable/movable devices. In the former applications, power is supplied directly to the electrical devices, whereas in the latter, a battery storing energy is necessary. Wireless transmission of electrical energy can be achieved with techniques that can be broadly classified as far field (radiative) and near field (nonradiative). The former class is particularly suitable for transmitting information at low power. High power radiative transfer is in fact undermined by the waste of energy in free space and thus by the low efficiency when omnidirectional antennas are used and by safety issues and the need for sophisticated tracking systems when directional antennas are used to supply power to mobile objects. The technique that has been recognized so far as the most promising for transmitting power belongs to the class of nonradiative techniques and is based on the magnetic coupling in a resonant system. Several applications of this technique have been proposed, which show that a high efficiency in transmission can be achieved; however, the distance of transmission and amount of power are still limited, thus, restricting the practical applicability of this technique. It has been shown that a higher efficiency can be obtained at a distance of transmission a few times larger than the largest dimension of both objects involved and can be reached with two resonant coils of the same resonant frequency magnetically coupled [10,11]. The resonance condition in the coils is essential as the magnetic coupling between two air-core coils is intrinsically weak [12]; it can be obtained by arranging capacitance in series or in parallel with the coil inductance. The exchange of energy (and thus the efficiency) between the coils can in this way be raised, whereas ...